On this issue of %pen I can think of three solutions

1. Remove percentile penetration as an itemization option and then nerf Ar/MR values to reasonable levels. Right now a tanky target is either immortal to folks without Whisper/Void or they're a wet paper bag to people with it.

2. Make Void/Whisper penetrate 50% of a target's resist that EXCEEDS 60. No, not bonus resist. Making it hit bonus resist would hit soft targets building resist harder than tanky folks, as weird as that sounds. Setting the cut-off point at 60 makes it equally effective against any tanky target. The break-even point would be at around 200ish resist with the new version getting better above that value. This would mean buying these items would be a choice rather than them simply being the best damage amplification items in the game. Absolutely vital to this option is changing penetration calculations back to the old way, flat first and THEN percentile.

3. Remove percentile penetration and turn items like Void and Whisper into flat penetration items, tools for champs who want to pop soft targets. Then alter Crit so that it grants percentile penetration on your auto-attacks rather than a chance to deal double damage. This would remove variance from Crit, remove 1% Crit chance cheese, make it so Crit users don't vaporize soft targets instantly, and maintain their ability to crack hard targets. Resist values would need to be fiddled with to keep everything running well.

So!

Do folks have a preference here? What would you like to see happen? What would you absolutely NOT want to see happen?